These guys are very good at filling planets with population and at holding on to worlds, but quite bad at diplomacy. Tactically, they have no particular strengths or weaknesses. Collective government is pretty strong (+intel defense, +construction capacity, immune to morale, -science, no elite officers), but in a game with elite officers, that penalty is actually a penalty. Basically, they're all about the macro advantage afforded by high population. I'm sad that I didn't find a way to work in the "nomnomnom" aspect of the trope - perhaps a special trait that increases EP yields from eating civilians and/or liquidating infrastructure is in order. I'm also kind of considering building a trait that gives all this race's ships the Biological special ability from the CMC; not sure whether this should also increase maintenance costs of their units, but I don't know by how much.

Superiority Complex - Until roll a 10 on 1d10, cannot conduct diplomacy with newly-met empire. Roll each month; declarations of war and hostility unaffected.

Very similar on a holistic level to the bugs - definitely have a macro advantage for booming econ between being able to control population growth and the discount on infrastructure, but bad at diplomacy. While the bugs have strong defense, the bots have strong offense, but suffer from high maintenance costs (both on military units and on their own populace), and since robotic census is pretty expensive, you're paying economically for your versatility. I'm most worried about balance on these guys, but I think I hit the main themes of the trope well.

Savages:

Combat Respect - Treaties with any given power have a 25% chance of failure until you've met their forces in battle

Honorable - All bonuses and penalties to breaking treaties are doubled

Warmonger - +20% bonus to declaring war, 15% chance to refuse any off of armistice

In stark contrast to the bugs and the bots, the noble savages have basically no macro advantages, but are very strong in combat, both in space and on the ground. They're bad at spying, but OK for defense against spies, and suffer from some diplomatic restrictions. They're mighty good at declaring war, though... Also, while the bugs and the bots are restricted to Collective governments, the Savages can choose any flavor of government they like (Military Meritocracy, for example). As far as the tropes go, I probably could cut out some of the naval bonuses, but they're rather nice.

Slow Gestation - Check for population growth every 18 months rather than every 12

Sneaky - Reduce the length of pursuit scenarios by 1 turn, pursuer must use one fewer squadron, -10% to chance of being discovered if using stealthy movement

The puppeteers have some serious macro penalties, but gain excellent spies, excellent diplomacy (not only no restrictions like the previous three races suffer from, but bonus intel for diplomacy), and a few tricky tactical bonuses to space combat. Not a race for a stand-up slugging match, but in a 5-person game, a little plausible deniability could go a long way. I'm a bit concerned that they might be underpowered, but that's something only playtesting will tell. I considered the Telepathic and Espionage Expert traits, but I'm not sure hidden forces will be a thing, since we're going to be playing face-to-face / board game style. If playing by PBeM, substitute Espionage Experts for Sabotage Experts to taste. There's also no 'dark X' side of the coin here, but I'm pretty OK with that. Elsewise, hits the tropes fairly well.

Merchants

Efficient Operatives - Maintenance on Intel points if 1/12 rather than 1/10

Expert Scientists - -5% to tech investment threshold

Friendly - Other powers take -15% to break treaties with this power, -10% to declare war against

Gifted Negotiators - 3 free intel points per turn for diplomacy only

Logistics Experts - Supply range of 3 starlanes instead of 2

Mercantile - +20% commerce income

Open Society - All intel missions against this power are at -1 difficulty

The merchants are kind of a happy middle ground. They've got some economic stuff going for them in terms of EP generation, which serves similarly to the macro advantage of the bugs and the bots, but they also have small diplomatic bonuses and a choice of governments. They have the strategic advantage of long supply lines, but suffer from weak defense against spies and from expensive ground units (justified as having to pay mercenaries). Think the Italian states of the Renaissance period. I'm concerned that, as with generalists in many games, the merchants will get stomped by specialists (namely everybody else). It would be possible to specialize them further, but I'm not sure trade / civilian fleets / supply are a particularly strong thing to specialize in. Also weird is that they kind of have two cross-purpose traits - Efficient Operatives makes it cheaper to hold on to lots of defensive intel, which is then rendered less effective by Open Society. Not entirely happy with that; could swap Efficient Operatives for another 'spy' trait of the same price to put a particular spin on them. Mission Specialist: Assassinate Officer significantly changes the way the race feels, for example, from a bunch of merchants to a race of mercenaries, while Insurgency Specialist puts a more social / cultural powerhouse spin on things (a bit more like modern Japan, perhaps).

So, that's what I've got. In a five-player match, one of each species, I'm really not sure how things would roll out. I think the puppeteers and bugs would get along great, as the 10 points of free diplomatic intel can be used to counter the language barrier, allowing treaties with no chance of failure. This leaves the savages, the bots, and the merchants to kind of hack things out amongst themselves... That could go quite poorly for the merchants, leading to possibly a "Poland between Germany and Russia in World War 2" situation, or to a small, staged engagement between the merchants and the savages in order to satisfy the savages' combat respect and allow an alliance with the machines... Really depends on the players, there, and possibly on the order of contact between species.